I have just bought a new spot light fitting for my kitchen and last night I tried to wire it to the fitting that was already in place.

I have a looped circuit, but the wires currently go into 3 separate circuit boxes, and the new light fitting only has one, long circuit box. Should I group all the blues together and put them into one hole and the same for the brown?

Your description does not give enough information.
Fitting of non UK style lights is one of the biggest causes of requests for help on this forum.
Go to projects page and see if that helps.
Be very careful with blue wires as often one of these wires is line and rest neutral and if you get them mixed up it is a real pain trying to sort out after.
It is common that the light is only feed with blue wires and the brown wires are what is called loop as in UK the ceiling rose not only suspends the lamp but acts as a junction box to next lamp.
Eric

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